Is this outfit okay to go and ride horse?

If I were going riding, I'd wear nice worn jeans (without holes) and a nice summer tee or tank. If it's cooler, or you think you're going to be getting too much sun on the ride, wear either a long sleeve tee or maybe flannel shirt. I'd wear my cowboy boots [can't help it, I'm American], only if you have them. I wouldn't go out and buy new ones just for the ride - any older boots you have should be fine. Personally, I'd dress in clothes and boots I know I'm comfortable in, not new clothes. Ask your friend what she's wearing. If she's like me, she'd probably LOVE giving you advice what to wear...then you can't go wrong. Hope this helps and you have a great time.